Iraqi police have unearthed two mass graves in the western city of Ramadi, with bodies of about 40 people killed by ISIS during the militant Sunni group's reign of terror in the city.

Bodies of women and children were among those found in the two graves, along with bodies of men in civilian clothes, said the officials.

The officials said ISIS militants who were captured and arrested after Iraqi forces routed the extremists led authorities to the site of the mass graves, inside the city's soccer stadium.

Ramadi, the provincial capital of Anbar, fell to IS (Islamic State) in May. It was liberated in December.

There have been many instances of mass graves being uncovered in territory wrested from IS militants in Iraq and Syria - thousands of people have been killed in summary and extrajudicial killings by the Sunni militants and the graves have been a dark testimony to the group's brutality.

In June 2014, some 1,700 Iraqi soldiers were captured and then killed by ISIS militants when they overran Saddam Hussein's hometown of Tikrit, Daily Mail Reports.

At the time, the soldiers were trying to flee from Camp Speicher, a nearby army base where they were deployed. Mass graves with hundreds of Iraqi soldiers' bodies were found after the city was liberated in April 2015.

In December, the U.N. human rights office in Iraq said it received reports of 16 mass graves discovered near the town of Sinjar after it was liberated from the so-called “Islamic State” group the previous month.

Among the first mass graves uncovered in Sinjar - within days of ISIS forces being pushed out of the town - was one near the town's center that has been estimated to contain the bodies of 78 elderly women, and another, about 15.

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